I have now burned the latest MacPup .iso to two different discs, and my MacBook will not boot from either of them. I have held down "c" while starting, as well as "option", but in the former case the disc just ejects and OSX starts. In the latter case, the Mac hard drive (with OSX) is the only boot option that appears.

Macpup is for PC's ,most of the time it won't run on a macbook. This is noted in the release notes for every version of Macpup we have released. The goal of Macpup is to make older pc's look cool and run great like a Mac. Not to make puppy run on a apple computer.